This invention relates to gas turbine combustors and, in particular, to combustors having primary and secondary combustion chambers divided by a venturi.
A combustor in an industrial gas turbine typically has dual combustion chambers. A venturi typically divides the combustor into primary and secondary combustion chambers. Combustion gases generated in the primary chamber flow through the venturi to the secondary combustion chamber. The conventional venturi chamber generally has dual-walls with cooling gas passages between the walls. Cooling air enters an upstream inlet to the passage between the walls of the venturi. The cooling air flows out from an axial end of the venturi. A conventional venturi chamber is disclosed in U.S. Pat. No. 5,575,146.
Conventional dual-wall venturi chambers exhausts cooling air from the annular passage between the walls of the venturi. The air from the venturi chamber is discharged from the axial end of the venturi chamber adjacent the combustor liner wall in the secondary combustion chamber. The combustion air is discharged from the venturi in an axial direction paralleling the centerline of the combustion chamber. The air from the discharge end of the venturi flows into the secondary combustion chamber along the liner wall of the combustor and flows in a direction generally parallel to the centerline of the chamber. The air discharged from the axial end of the venturi generally flows along the surface of the liner wall and does not quickly mix with the combustion gases in the combustion chamber.
There is a long felt need for combustors having robust mixing of compressor air and combustion products. This need also exists with the gas flow through a venturi. Robust mixing of air and combustion products tends to reduce emissions, such as reduced nitrogen oxides (NOx).